Pump



g i4? l H. M. GEYER mm.,

PUMP

2 Sheets-Sheet 2 Filed Deo. 5, 1944 fad "i ATTORNEY@ latel'ited July 9, 1946 UNITED f vSTAT PUMrjv Howard M. Geyer and Howard Carson,vDayton, Ohio, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application December 5, 1944, Serial No. 566,6781

1 y This invention relates to highY pressure pumps for use with hydraulically operated apparatus such as, for example, the servo-motor which ade justs the pitch of airplane propeller blades.

An Vobject of the invention is to provide a durable pump which, in proportionto its size, is capable of v delivering liquid under relatively highV pressure and which can be produced at relatively low cost. Therefore it is the aim of the invention to provide a construction which involves the use of a relatively small number of parts. To acomplish this, the pump comprises a housing providing a plurality of cylinders each receiving a pair of oppositely reciprocating pistons and a drive shaft which provides the movable Ivalve members of the pump and which carries the means for imparting positively to the piston reciprocatory motion in both directions.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings'wherein a preferred embodiment of the present invention is clearly shown.

Inthedrawings: I f

Fig. 1 is a fragmentary longitudinal section viewV of a portion of an vairplane propeller pitchregulator showing a side View of apump embodying the invention. Y e

Fig. 2V is a sectional view on line A2 2 of Fig. 4.

Fig. 3 isa sectionalviewon line 3-.3 of Fig 2 Fig. 4 is a sectional View on line 4--4 of Figs. 1 and 2. Y f

Fig. 5 is la perspective view of a fragment ofthe longitudinal sectionvof the pump showing details of construction on a larger scale than thepreceeding figures.

Fig. 6 is a view of one side of the pump shaft. Fig..7 is a sectionall View on line 1 1 of Fig. 6.

1o Claims. (o1. 10s-173) l v13 Yis a View similar to Fig. 11 showing the relation lbetween the vbearing Washer, shown. in

' sectionk in Fig. 9 and its associated piston.

` for sakeof clearness.

15 is a chart showing the relation of pis- Fig. v14 Vis a view in the direction of arrow `I4 of Fig@v 13, all but` one of the pistons being omitted tons` positions and valve positions.

In Figfl, there is shown anadapter of tubular formation comprisingparts I0,'II and I2 AWhich are secured together 4by screws, lsuch as screw I3; and-the -part I2 is attached to a portion I4 oi the engine frame indicated'in dot-dash lines. I his adaptersurrounds the enginedriven shaft @not shown) which carries the propeller hub. To

the propeller hub there is secured a housing plate I5l carryinwg"a` cover I6. Themembers I5 and I6, which areof annular formatiomytogether with the tubular adapter `part I0 and annular sealing members II and I8,v provide an annular chamber for enclosingpartslof'an hydraulic system for -controlling the; applicationof hydraulic pressure toservo-motors which rotate the propeller blades about their root axes in order to govern the speed of the engine. Y One of theparts of the hydrau1ics`ystem`ris thepump 20 which will now bezdescribed. Y 'K 'f Pump -20 comprises a housing 2| having a cylindrical part 22received by the cylindrical Wall 23 deningavrecess 24 of. housing I5 which enclosesthe pump. From the part 22, there ex- Fig. 8 is a View of that side of the pump shaft diametrically opposite tothe side shownin Fig. 6

and a sectionalview of a bearing washer assembled with the shaft. l

Fig. 9 is a side view of a wobble plate to be 'assembled with the shaft shown in Fig. 8 and a'sectional view of a bearing washer assembled therei Y n driveshaft 40 having an inletpassage 4I. which f r y Fig. 10 is a side View of a clamp Washer to be assembledwith the pump shaft). Y

Fig., 11,is a diagrammatic 'view showing relation between the `rbearing Washer, vshownV in the tends a IIiange 25 having holes 26 for receiving screws by whichV the pumphousing Y2l is secured to theV plate I5. When the housing 2| is secured in'position, its outlet passage 21 is. placed in communiation with a passage 21a of plate I 5 leading tov-a. manifold having parts 28, 29 and 30 for conducting pressure 1*fluid to other parts of the hydraulic "system,4 A Washer 3l seals the joint between the passages 21- and 21a.' For details'of. the systems, reference is made to Blanchard and Mac- 'NeilPatentNa v2,307,102, filed January 15, 1943.

`V`.R'eferrin'g tof1ig; 2, passages 33r and 34 connect passage 21`withthe central bore 35 in the housing f2I which provides a bearing for the pump will be submerged with the hydraulic fluid or oil contained Within the housingparts vI5 and I6 when rotating, the annular rotating level being indicated approximately by line x-x in Fig. 1.

*i Obliqueipassage 42 connects inlet 4I with a recess 43`fprovided'by the shaft 40 as shown 'in Figs. 2, 3, and '8.' This'recess'43 is wide enough to reach to 'two vtmdsometimes thru'portsl 44, each leading toadisplac'ement chamber within a pump 'cy- 3 linder 45, there being five pump cylinders in the disclosed embodiment. Each port 44 is provided by drilling the holes 46 and 41 which are plugged.

Each cylinder 45 receives a pair of oppositely reciprocating pistons. The pistons to the left ol section line 3 3 of Fig. 2 are marked I to V, and those to the right are marked I to V. During practically all of the travel of a pair of pistons away from each other the port 43 is so disposed as to connect the pump inlet with the cylinder enclosing that pair of pistons.

each other the port 44 of the cylinder enclosing that pair of pistons is connected with the pump outlet 21 by a recess 59 (Figs. 2, 3 and 6) a channel 5| and an annular groove 52 always connected with passage 34, The channel 53 connects the recess 5B with an annular groove '54 for supplying lubrication to the shaft bearing more remote from the recess 50, v

The valve recesses 43 and 55 are diametrically opposite and are separated by blocking areas A and B each of a width slightly exceeding the width of each port 43 as best shown in Fig. 15. In that figure line M-M represents a planepassing through the center of each cylinder 45. Line Z--'m-1z, which represents the relation of movement of pistons I to Vvtorotation of the pump shaft, passes through the centers of short horizontal lines marked I to V which represent the inner ends of these pistons. Line Z-m-n' which represents the relation of movement of pistons I to V to the rotation of the pump shaft, passes through the center of short horizontal lines marked I to V which represent the inner ends of these pistons.` Lines Z-m-n :and Z-mn' are sine curves denoting that the motion of the pistons is simple harmonic motion in relation to shaft rotation. The rate of piston travel relation to shaft rotation near the beginning and the end of stroke is relatively small.

When pistons I and I are beginning to separate, the port 441, of their cylinder 45 is blocked by the shaft surface B between recesses 50 and 43. At that instant the pistonsII, II, and III, and III', which are separating, are in the positions shown in Fig. and their respective cylinder ports 441i and 44111 are connected by recess 43 with the pump inlet. At the same instant, the pistons IV, IV', and V, V. which are approaching, are in the positions shown and their respective cylinder ports 441V and `44y4are connected with the pump outlet by recess 59. When any pair of pistons, such as I and II, arriveV at the inner ends of their strokes,l their cylinder port is blocked by shaft surface B; and when at the outer ends'of their strokes, their cylinder port is blocked by shaft surface A. During their brief intervals when a cylinder port'is blocked, the rate of piston travel is low; therefore the amount of hydraulic braking is inconsequential.

The pistons I to V are caused to reciprocate by rotation of a wobble-plate 60 (Figs. 1,2, 6 and 8) integral with shaft 40. Motion of plate 60 is imparted to the inclined heads 'l0 of the pistons through an `interposed wobble-ringl of bearing bronze journalled on an eccentric boss B2 which is located next to a groove 63 between the boss 62 and a flange 64 having a wobble surface `B5 for engaging the inner side plane surfaces ofthe 7 piston heads 10 which are received by the groove 53. The center of the shaft 40 is indicated at r401; and the center of the boss B2' is indicated Vat 62c of Figl 11. Each head 1S of a piston-Ito Vis During practi; cally all of the trail of a pair of pistons toward which extends at right angles to the plane upper face of the piston head 'l0 and is received by a hole in the ring. As the wobble-plate 6i] rotates, the center of wobble-ring,r e! oscillates in the path denoted by circle Sip in Fig. 1l, and causes each of the five pistons to rotate as denoted by the circles lip. This connection between the wobble-ring and the piston heads accomplishes two things, namely: (l) The outer surface of each Apiston head ll) is caused to be in coincidence 'with the plane of the adjacent surface of the ring Si so that the force exerted by the ring to move the pistons inwardly is distributed over the engaging surfaces of the ring and piston head.

yThere can be no vcooking of a piston head surface relative to the ring surface, and no point or line contact. A surface contact is insured. (2) Since each piston must rotate as it reciprocates, there is no straight line scoring of the engaging surface of the piston and cylinder. The pistons are positively moved in both directions, namely: they are moved in by the wobbleplate 60 and out by the flange B4 whose surface B5 operates as a wobble-plate.

The foregoing applies to the operation of pistons I to V which are operated by the unit 80 (Figs. 9, 13 and 14) having parts corresponding in function to the similarly numbered parts of Figs. 8, 1l and l2, the reference numbers of the parts of Figs. 9, 13 and 14 having a prime aixed. The unit 8@ is attached by a key 8l (Fig. 2) to kthe shaft 4D. A washer 82 is located next to wobble-plate 6G; and, by means of a nut the unit 80 is forced against a shoulder 84 of shaft 40. This nut is the vhub of 9| of a gear 90 which meshes with `a gear 92 integral with part l0 (Fig. l) having its axis substantially in coincidence with the axis of the engine shaft. After screwing on the gear hub 9i, a hole is drilled through the hub and shaft and a pin 93 is driven through. As the housing l5, I6 rotates around the axis of the engine shaft, part lil being fixed, the gear BB rotates at relatively high speed.

It will` be noted by referring to Figs. 8 and 9 that thev eccentric bosses 62 and 61,y are diametrically opposite. Therefore when wobble-ring 6I is up (Fig. 1), the wobble-ring 6I` is down. The purpose of this arrangement isto obtain` dynamic balancing of the rotating'parts with respect Vto the aXis of shaft 49. rIfherefore the crank pins 1I (Fig. 12) extend from the upper portions ofthe inclined surfaces ofthe heads 10 of pistons I to V; andthe crank pins 1I (Fig. 14) extend from the lower portions of the inclined sur` faces of the heads 10' of pistons I torV. Y y

The motions positively imparted through the wobble-members by the shaft to Vthe pistons in both directions areV simple harmonic motions.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scopeof the claims which follow. y

What i's claimed is as follows: 1. A fluid pump comprising a housing having a central bore and aplurality yof cylindrical displacement chambers parallel to the bore and equally spaced in a circular row rconcentricV with the bore, pistons reciprocable in the displacement 0 chambers, displacement chamber` inlet and, outletports each connecting a displacementv chamber with the bore, a rotatable shaft journalled in ythejbore Yand rhaving inlet` and. outlet recesses I l rotatable past the ports andfseparatedlbyvalve connected with the ring 6| by a crank'pin' 1| 'i5 lands provided by shaft surfaces closely tting the-bore, a fluid inlet ductfconnected-witn the h inlet recess ofthe shaft,v a single fluid outlet duct for all of the displacement chambers'connected with the outletrecess ofthe shaft, and means operated by the shaft for imparting reciprocating motion to the pistons'and so related to the'shaft recesses that, duringan intake stroke of a piston,

'its chamber port is connected with the inlet recess of the'shaftand, 'during the dischargeY stroke of a piston, its'chambjer port is connected withV the outlet'recess oftheshaft, each chamber rport being completely blocked by a valveland at the' blocked by a valve land, is minimized.

, 3. A fluid pumpaccording to claim 1 further characterized by the fact that the inlet duct is provided by a passage in the shaft for connecting a supply of fluid with the inlet recess of the shaft within the bore, and by the fact the outlet ductfrom the outletrecess of the shaft is provided by a longitudinal groove in the shaft and by an annular groove in the shaft longitudinally displaced from the chamber ports and connected with the longitudinal groove and by a passage in the housing connected with the annular groove.

4. A fluid pump comprising aj housing having a central bore and a plurality of cylindrical displacement chambers parallel to the bore and equally spaced in a circular row concentric with the bore, pistons reciprocable in the displacement chambers, ports each connecting a displacement chamber With the bore, fluid inlet and outlet ducts, a rotatable shaft journalled in the bore and having valve means for connecting chamber ports with the inlet duct during intake strokes of their associated pistons and for connecting chamber ports with the outlet duct during discharge strokes of their associated pistons and means operated by the shaft for imparting reciprocatory movement to the pistons and for imparting rotary motion during reciprocation whereby longitudinal scoring of the contacting surfaces of pistons and chambers is avoided.

5. A fluid pump comprising a housing having a central bore and a plurality of cylindrical displacement chambers parallel to the bore and equally spaced in a circular row concentric with the bore, pistons reciprocable in the displacement chambers, ports each connecting a displacement chamber with the bore, fluid inlet and outlet ducts, a rotatable Shaft journalled inthe bore and having valve means for connecting chamber ports with the inlet duct during intake strokes of their associated pistons and for connecting chamber ports with the outlet duct during discharge strokes of their associated pistons, and means operated by the shaft for imparting reciprocatory movement to the pistons positively in both directions and for imparting continuous rotary movement to the pistons during reciprocation in both directions whereby longitudinal scoring of the contacting surfaces of pistons and chambers is avoided. Y

6. A fluid pump comprising aA housing having a central `bore and a plurality of cylindrical displacement chambers parallel to the bore and equally spaced in a circularv row concentric with the bore, pistons'reciprocable'in the displacement chambers,` ports each connecting a displacement chamber with the bore, fluid inlet and outlet ducts; a rotatable shaft journalledin thevbore and having valve means for connecting chamber` ports Withthe inlet duct during intake strokes of 4their associated pistons and for -connecting chamber ports with the.A outlet Yduct during discharge strokes of` their associatedpistons,v andv means Operated by the `shaft for causing, each piston gto complete a cycle of reciprocations and simultane- Y ously 'to rotate one vrevolution for Vav revolution. of the shaft wherebylongitudinal scoring of the contacting surfaces of the pistons and chambers is avoided. .f v f 7,. A uid pump comprising a housing having a central bore and a pluralityy of'cylindrical 'displacementY chambers parallel Yto the .-bore'and .equally spaced ina circular-'row concentric 'with the bore, pistons reciprocable in the displacement chambers-portseach connecting a displacement chamber f with the fbore, fluid inlet and outlet ducts, -a rotatable shaft journalled in the bore and having valvev means for connecting chamber ports with the inlet duct during intake strokes of their associated pistons and for connecting chamber ports with the outlet duct during discharge strokes of their associated pistons, piston heads having inner and outer parallel plane surfaces oblique to the axis of the piston, a flange on the shaft having an oblique plane surface for engaging the inner surfaces of the piston heads, a wobble-washer oblique to the shaft for engaging the outer surfaces of the piston heads, a circular boss provided by the shaft eccentrically thereof upon which the wobble-Washer is journalled a wobble-plate provided by the shaft obliquely thereof for engaging the wobble-washer, and

crank connections betweenv the wobble-washer and the piston heads whereby, as the wobblewasher is caused to wobble and move'eccentrically relative to the shaft, the pistons are caused to rotate in order to maintain their head-innersurfaces in the plane of the oblique surface of said shaft-flange and in order to maintain their head-outer surfaces in the plane of the engaging surface of the wobble-washer, and whereby rotation of the pistons avoids scoring of the contacting surfaces of the pistons and chambers.

8. A pump according to claim '7 further characterized'by the fact that the crank connection between the wobble-washer and the piston heads are provided by 'crank-pins which are fixed to the heads and extending at right angles to the outer surfaces of the heads and the wobble-washer is provided with holes for receiving the crank-pins.-

9. A fluid pump comprising a housing having a central bore therethrough and a plurality of bores therethrough to provide cylindrical displacement chambers parallel to the` bore and equally spaced in a circular row concentric with the central bore, two pistons oppositely reciprocable in each chamber, ports each for connecting a central portion of a chamber with the central bore, fluid inlet and outlet ducts, a rotatable shaft journalled in the central bore and having valve means yfor connecting chamber ports with inlet ducts during intake strokes of their associated pistons and for connecting chamber ports with outlet ducts during discharge strokes of their associated pistons, the ends of the housingl beyond which the shaft extends being provided with plane surfaces at right angles to the axis of the shaft, devices located adjacent the plane surfaces of the housing and so connected with the shaft as to limit longitudinal movement theresarcasm of in relation to the housing and having provisions for causing the pairs of pistons in the chambers to reciprocate in oppositedirection and to rotate while reciprocating in order to avoid scoringof the contacting surfaces of the pistons and cham+ bers.

10. A fluid pump according to claim 9 in which each piston has a head having parallel plane surfaces oblique to the axis of the piston and in which one of the devices includes afstructure integral with the shaft and the other is anintegral unit detacha-bly xed to the shaft, each struc-Y ture comprising a ange having a plane surface at right angles to the axis of the shaft and adapted to engage a plane at an end of the housing and having a plane surface oblique to Ithe axis of the shaft for engaging the inner plane surfaces of the piston heads, each structure comprising a circular boss separated from the flange by a piston-head-receiving space and providing a journal for a wobble-washer, said boss being eccentric to the axis of the shaft and oblique thereto, and each structure comprising a wobble plate oblique to the axis of the shaft for engaging a 8 wobble-washer5V and awobblewasher mounted upon theeccentr-ic boss of each structure and engageable with the outer surfaces of the piston heads, and with the wobble plate, and crank connections between the wobble Washers and the piston heads adjacent thereto whereby, as the Wobble-washers are caused to wobble and move eccentrically relative to the shaft, the pistons are caused to rotate in oider to'maintain their headinner-surfaces in the planes of the adjacent oblique surfaces of the iianges and in order to maintain their head-oute-'surfaces in the planes of the engaging surfaces of their adjacent wobble- Washers, and whereby rotation of the pistons avoids scoring of the contacting surfaces of the pistons and chambers, the two motion transmitting devices being so positioned relative to the shaft that their plates and washers wobble in opposite directions and that the axes of their eccentric, wobbleew'asher-journalling bosses are on n diametrically opposite sides of the shaft axis. Y

HQWARD M. GEYER. HOWARD CARSON. 

